The invention relates to an aerodynamic wind propulsion device, particularly for watercrafts, comprising an aerodynamic wing being connected to a steering unit located below the aerodynamic wing via a plurality of tractive lines, a tractive cable, a first end of the tractive cable being connected to the steering unit and a second end of the tractive cable being connected to a base platform, the aerodynamic wing having an aerodynamic profile which generates an uplift force in the direction of the tractive cable when the airflow direction is about perpendicular to the tractive cable.
According to this description, an aerodynamic wind propulsion device is to be understood as a device which might be used to drive a movable platform or vessel like a ship or the like. Further, an aerodynamic wind propulsion device is to be understood as a device which is driven by the wind and is movable with reference to a fixed base platform like a platform attached to the ground or fixed in the sea like e.g. for onshore or offshore wind energy plants.
A major problem associated with such aerodynamic wind propulsion devices as described beforehand is the control of the aerodynamic wing in use. In order to produce significant uplift forces by the aerodynamic wing which can be transferred via the tractive lines and the tractive cable to the movable or fixed base platform it is desirable to increase the size of the aerodynamic wing. However, the control of such large scale aerodynamic wings having sizes of 160 m2 and more is difficult and the loss of control of such large scale aerodynamic wings may result in a situation where the aerodynamic wing crashes and cannot be rescued.
WO 2005/100147 A1 discloses a positioning device for controlling a wing element which is connected via a tractive cable to a ship to serve as main or auxiliary drive. Such propulsion systems based on wing elements flying at high altitude and pulling the ship via a tractive force require large-scale wing elements and the control of such wing elements is a challenging task. In WO 2005/100147 A1 it is proposed to veer out or haul in the tractive cable in response to the flight condition of the wing element. Whereas by such a control mechanism a certain degree of flight control can be achieved, it is not sufficient to control the wing element in all flight conditions, in particular when the wind changes its strength or direction significantly.
To improve control of such wing elements in difficult wind conditions it is known from WO 2005/100148 A1 to couple a steering unit close below the wing element via a number of control lines and to connect the wing element to the nautic vessel via such a steering unit by a tractive cable extending between the nautic vessel and the steering unit. By this, control of the wing element can be improved but it is still a challenging task to control the wing element and specifically to steer the flight path of the wing element.
WO 2005/100149 A1 proposes various sensors to improve control of a wing element towing a nautic vessel. Whereas these and the former techniques may improve the steerability of aerodynamic wing elements it remains still a quite challenging task to efficiently steer and control large scale aerodynamic wing elements and control its flight path and conditions in an efficient way.
The set ups and techniques of aerodynamic wings and their control will significantly improve the steerability and options to control the flight path of such aerodynamic wings. However, it is desirable to provide additional control means which facilitate the control of aerodynamic wings, in particular in challenging control situations like starting and landing manoeuvres.
To improve steerability during starting and landing manoeuvres, WO 2005/100150 proposes a telescopic mast erected on the foredeck of a nautic vessel close to the fixing point of the tractive cable coupling the wing element to the nautic vessel. Using such mast, the wing element can be directly coupled to the top of the mast. Whereas such a technique may significantly improve manoeuvrability of the wing element during starting and landing procedure, the challenging task to improve the steerability of the wing element in various flight conditions and to improve the efficiency of such a steering technique remains.
While such a mast as proposed in WO 2005/100150 will facilitate the starting and landing manoeuvres, it is still a challenging task to safely control the aerodynamic wing while it is coupled to the mast and in the short time period after it has been decoupled from the mast in the starting manoeuvre and is flying at low altitudes. Still further, it is still a challenging task to control the flight path of the aerodynamic wing in the period of approaching to the mask at low altitudes and the period of coupling the aerodynamic wing to the mask after such approach in landing manoeuvres.
One reason for the problems associated with such starting and landing manoeuvres is the fact that the wind speed at low altitudes is different from the wind speed at high altitudes. Thus, the control at high altitudes is a different task than the control at low altitudes.
A still further problem associated with such starting and landing manoeuvres is the fact that large scale aerodynamic wings may transfer high forces to the mast when coupled to it.